On Sun, 23 Sep 2012 16:36:01 +0100, Farmer Giles wrote:

Yes, I have found lots of information about the fluke, but none of it
is very clear about how the parasite passes from the plant to the
person who eats it - ie does one have to eat the flukes themselves, or
their eggs, or is it transmitted in other ways?

Read the wikpedia article I previously mentioned, it's ingestion of a
stage of the liver flukes life cycle. It has a life cycle far more
complicated than adult egg hatch into small adult grows adult.

Also, as I asked, can they be removed by filtering?

Seems a bit of moot point if growing in anything other than drinking
quality water is out lawed. Filtering, depends how big the stages (note
plural) that are likely to be in the water are. UV treatment might be an
option but IIRC watercress needs a fairly hefty running water supply.

--
Cheers
Dave.